Is Your Distillation Process Damaging THC Content?

By Dylan Wilks, CTO

When potency and purity are required, it’s hard to beat distillates. Distilling cannabis oils is becoming more common as consumers are demanding higher potency and clear product. We’ve seen distillates that come in at 90+%, impressively potent! But not all distillates are the same. Depending on the specific distillation method and care taken, there’s a chance that the distillate contains less Δ9THC than you might think, sometimes lower than the starting product. Why is that? To answer, lets first explore how distillation works.

Distilling cannabis is just like distilling alcohol. You put the starting material in a container, heat it to a specific temperature and collect the vaporized material by cooling and condensing it. Cannabis is distilled at higher temperatures than alcohol, and often a vacuum is applied to the system which lowers the boiling point of the Δ9THC (or CBD) for distillation. The figure below shows a simple short path distillation setup.

Distillation setup

There is one difference between a cannabinoid molecule and an ethanol molecule - cannabinoids are much larger and more complex, 7 times as large to be more exact (314 g/mol for THC vs 46 g/mol for ethanol). This complexity opens up THC to chemical reactions.  And if you’ve taken any chemistry classes, you know that both heat and oxygen are very good at speeding up chemical reactions.  If both aren’t controlled well, you might not end up with pure THC in your distillate.

Most people think of Cannabinol (CBN) as the primary degradation product of D9THC.  While CBN certainly is a degradation component of Δ9THC, in the presence of heat and oxygen, it takes several steps to get there, and at least a few of these steps are stable at room temperature - in other words your “pure” distillate may very well have several degradation components included. We’ve been investigating this for more than six months now, and while we have seen many degradation products, the most common degradation product is commonly referred to as “dihydroxy-THC”, where an extra OH functional group is attached to the molecule. See the figure below for an example.

  dihydroxy THC : on the way to CBN but not quite there yet.

dihydroxy THC: on the way to CBN but not quite there yet.

So what’s the problem with these extra components? First, most evidence points to “dihydroxy” forms of THC being non-psychoactive. We’ve seen some distillates with up to 20% degradation products. That means you’re not going to get as much bang for your buck. What’s the point of distillation if you start with 60% THC, then only get to 65% when you’re done?  Second, we’ve noticed the taste and smell of distillates that contain degraded THC components are different than when they are not present - more burned tasting.  Finally, the point of distillation is to make a pure component. If you’re breaking down the component of interest, something within your distillation process is wrong and your product quality is suffering.  

What can be done to reduce these degradation products? While we aren’t distillation experts, we have a few ideas, if others know more about this definitely get in touch. 

  • First, make sure you are heating your product to the correct temperature and that it is well mixed so that no part of the product is exposed to too much heat.  
  • Second, make sure you have a good vacuum without any leaks.
  • Finally, and this is where the experts take over: distillation is like many processes; it’s a game of maximizing throughput. Using more heat or distilling the tails of the distillation flask for a long time will give you more product but going too far will mean quality issues. Finding a balance is the key.

Understanding the best process and when the right time to stop is where a good distillation artist is worth their weight in gold (or distillate, which is typically more expensive per gram than gold). Of course, having in-house testing capability with a device like LightLab makes it possible to ensure your product is pure, potent and consistent every time.